1. Field of the Invention
The present invention relates to the structure of a semiconductor module with a power factor correction (PFC) circuit.
2. Description of the Background Art
Use of a PiN (p-intrinsic-n) diode formed by using silicon (Si) in a semiconductor module for power control (power module) conventionally produces the storage effect of minority carriers to generate a recovery current. This is one of factors for loss increase of the power module. Such loss is reduced significantly by a Schottky barrier diode. So, in many cases, a Schottky barrier diode (SBD) formed by using Si is used in the conventional power module.
A semiconductor element using a wide bandgap semiconductor is regarded as a promising element to function as a next-generation switching element capable of realizing high breakdown voltage, low loss, and high resistance to heat. Patent literatures 1 to 5 listed below each disclose an example in which a semiconductor device formed by using silicon carbide (SiC) (SiC device) that is a typical wide bandgap semiconductor is applied in a power module.    Patent Literature 1: Japanese Patent Application Laid-Open No. 10-93015 (1998)    Patent Literature 2: Japanese Patent Application Laid-Open No. 11-233712 (1999)    Patent Literature 3: Japanese Patent Application Laid-Open No. 11-510000 (1999)    Patent Literature 4: Japanese Patent Application Laid-Open No. 2003-18862    Patent Literature 5: Japanese Patent Application Laid-Open No. 2006-149195
A PFC module including a rectifying diode bridge and a power factor correction (PFC) circuit is known as one of power modules with diodes. A diode bridge of a conventional PFC module is constructed of Schottky barrier diodes made of Si. Meanwhile, voltage drop in a forward direction (forward voltage (VF)) of the Schottky barrier diode made of Si increases considerably if a breakdown voltage is several hundred volts or higher. So, if used in a power module for high-voltage control, the Schottky barrier diode made of Si may increase loss of the power module more seriously than a PiN diode.
In contrast, a Schottky barrier diode formed by using SiC makes it possible to maintain a forward voltage at a low level even if a breakdown voltage is several hundred volts or higher. So, a power module with low loss and excellent recovery characteristics is achieved by applying a Schottky barrier diode made of SiC in the power module. However, an SiC device entails higher cost than an Si device. So, manufacturing cost is increased if a power module is formed as an SiC device.